Our overall objective is to determine the influence of timing of ART initiation and alcohol consumption on HIV disease course, including detailed analysis of important events occurring shortly after HIV acquisition. ART initiation immediately after HIV infection (during Fiebig stages I-II) largely results in smaller HIV reservoir and lower HIV-associated systemic inflammation, which has been linked to non-AIDS morbidity and mortality. Immediate ART also reduces HIV-associated bacterial translocation and may prevent dysbiosis, an alteration of the intestinal microbiota that has been linked to increased systemic inflammation. Immediate intervention is not, however, generally feasible and more information is required about the consequences of starting ART at later time-points, but still early after acquisition. The proposed study will be conducted in Lima, Peru, in our cohort of 180 MSM with acute (Ab-, HIV RNA+) or recent (= 3 months) HIV infection. Alcohol use disorder is present in ~50% of HIV-infected MSM in our cohort, which is four times higher than that seen among males in the general Peruvian population. Although the role of alcohol use in HIV pathogenesis and disease course remains unclear, some studies show a correlation with accelerated disease progression. In animal models and clinical studies, both acute and chronic alcohol consumption have been linked to bacterial translocation and activation of the innate immune system, which can lead to increases in pro-inflammatory cytokines. The effects of alcohol resemble early post-infection changes in bacterial translocation and pro-inflammatory cytokines induced by HIV and their impact on HIV disease course before and after ART initiation remain unexplored. Specific Aim 1: To determine the relative long-term benefits of immediate vs. early vs. delayed ART initiation. We will study outcomes after 1.5 and 3.5 years in MSM diagnosed with acute or recent HIV infection. We will examine outcomes in 3 groups based on time of ART initiation: a) immediate: during FI-II (N~30), b) early: during FIII-V (N~50) or c) delayed: at 24 weeks after diagnosis (N~80). We anticipate that CD4+ T cell counts and peripheral inflammatory markers in the FIII-V group and the delayed group will approach those in the immediate treatment group (FI-II) over time; in contrast, we expect that those started ART at early or delayed time point will have persistent changes in the GI microbiome and in the HIV reservoir. Specific Aim 2: To determine the impact of alcohol use on the relative long-term benefits of immediate vs. early vs. delayed initiation of ART. We will examine the impact of alcohol use on critical events in HIV infection. We hypothesize that dose-dependent alcohol-induced changes will compound the negative effects of HIV and lead to greater levels of dysbiosis and inflammation, higher early plasma HIV RNA, and greater seeding and persistence of HIV DNA in participants with high-level alcohol use. We will assess viral load, GI microbiome and metagenomics, pro-inflammatory cytokines, production of msRNA and analyze the impact on alcohol use in all subjects prior to ART initiation and among ART-adherent participants with persistent viral suppression.